1. Field of the Invention
This invention relates to improved pneumatically operated control means for a vehicle transportation system or the like and, in particular, to an improved thermostat construction therefor and to an improved pneumatically operated positioning construction therefor.
2. Prior Art Statement
It is known to provide a thermostat construction having valve means for directing a pneumatic signal to a pneumatically operated control device in relation to the force differential between the temperature sensed by a temperature sensing means thereof and a temperature setting of a temperature setting means thereof.
For example, see the following two items:
(1) U.S. Pat. No. 3,263,925--Joesting
(2) Copending patent application Ser. No. 864,674, filed Dec. 27, 1977, now U.S. Pat. No. 4,192,453--Frankenberg
It appears that the thermostat construction of items (1) and (2) above each has the temperature setting means and the pneumatically operated temperature setting means thereof acting on the valve unit along a longitudinal center line axis of the valve unit and the setting means.
It is also known to provide a thermostat construction having a valve actuating lever pivotally mounted to the construction with the temperature setting means and the temperature sensing means of the construction acting on the lever.
For example, see the following item:
(3) U.S. Pat. No. 3,580,502--Duchek
It appears that the thermostat construction of item (3) above has the temperature setting means acting on one side of the pivotally mounted lever thereof and the temperature sensing means acting on the other side thereof.
It is also known to provide a pneumatically operated positioning construction having valve means for directing a pneumatic signal to a positioning chamber thereof in relation to the force differential between a pneumatically operated setting means thereof and a feedback means of the positioning chamber.
For example, see the following item:
(4) Copending patent application Ser. No. 864,374, filed Dec. 27, 1977, now U.S. Pat. No. 4,178,837--Frankenberg
It appears that the pneumatically operated positioning construction of item (4) above has the pneumatically operated setting means thereof and the feedback means of the positioning chamber operatively interconnected to the valve unit to act along the longitudinal center line of the valve unit and of the setting means and feedback means.